Lankford, Thomas E. Jr.Targett, Timothy E.Gaffney, Patrick M.2015-12-092015-12-091999Lankford et al.: Population structure in Micropogonias undulatus. Fish. Bull. 97:884-890 (1999)0090-0656http://udspace.udel.edu/handle/19716/17288Publisher's PDF.Genetic population struc- ture in Atlantic croaker ( Micropogonias undulatus Linnaeus) was examined by using the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis of mi- tochondrial DNA (mtDNA). Juvenile croaker from three U.S. Atlantic locali- ties (Delaware, North Carolina, and Florida) and one Gulf of Mexico local- ity (Louisiana) were screened to docu- ment the magnitude and spatial distri- bution of mtDNA variation in M. undulatus ; to evaluate the integrity of Cape Hatteras, North Carolina, as a genetic stock boundary; and to estimate levels of gene flow among Atlantic lo- calities to provide an improved basis for future decisions regarding coastwide management of this fishery resource. RFLP analysis of the ATPase 6 and D-loop mtDNA regions revealed a total of 15 composite haplotypes in 93 indi- viduals. Monte Carlo simulations re- vealed no geographic heterogeneity in mtDNA haplotype frequencies among Atlantic localities and no evidence that juveniles collected north and south of Cape Hatteras originated from sepa- rate gene pools (net sequence diver- gence=–0.002%). There was significant heterogeneity between Atlantic and Gulf of Mexico samples, suggesting re- stricted gene flow between these two re- gions. Analysis of molecular variance also indicated regional (Atlantic versus Gulf) population structure, but pro- vided no evidence that Cape Hatteras represents a genetic stock boundary. AMOVA indicated relatively high gene flow ( N e m U = 12–23 effective female mi- grants per generation) among Atlantic localities. These findings are consistent with 1) a single genetic stock of M . undulatus on the Atlantic coast and 2) separate, weakly differentiated stocks in the Atlantic and Gulf of Mexico.en-USArticle